Relationship between karst rocky desertification and its distance to roadways in a typical karst area of Southwest China

摘要

The presence and conditions of roadways determine the utilization of natural resources, which exert direct and indirect influences on karst rocky desertification (KRD) in undeveloped karst areas. This paper addresses the relationship between KRD and its distance to roadways in Pingguo County, a typical peak-cluster depression area in Guangxi Zhuang Autonomous Region in Southwest China, focusing on the three time periods of 1994, 2001, and 2009. KRD maps for each time period were interpreted by using remote sensing and GIS technology in buffer zones, which are 4.0 km wide and subdivided into eight strips of 0.5 km wide each. They are located alongside various classes of roadways, namely trunk, town, village, and unpaved roadways. Results demonstrate that slight KRD is the major type in buffer strips on both sides of roadways, which tends to decrease with an increase in distance to road baseline. In contrast, moderate and severe KRD cases cover relatively limited areas, which tend to change less rapidly. Moreover, these two KRD cases are less related to their distance to trunk and town roadways than to village and unpaved roadways. Therefore, the distance to roadways affects slight KRD distribution more than moderate and severe KRD. Temporal KRD patterns indicate that slight, moderate, and severe KRD areas alongside all roadway classes have comparatively similar trends in the periods of 1994, 2001, and 2009 KRD areas alongside various classes of roadways in the three periods (except some of those alongside the town and trunk roads) rank as follows from highest to lowest, 2001, 2009, and 1994. However, the total area in town and trunk roads is relatively small and varies little with distance from strip-to-road. KRD alongside various roadway classes is affected jointly by historical policy, distance to roadways, and landscape.